1. Field of the Invention
The present invention relates to a vertical magnetic recording head device that applies a magnetic field to the surface of a recording medium in a vertical direction to record information on the recording medium.
2. Description of the Related Art
Vertical magnetic recording head devices have a laminated structure in which a return yoke layer is provided on a main magnetic pole layer, with a non-magnetic insulating layer interposed therebetween, in a surface facing a recording medium. The main magnetic pole layer and the return yoke layer are magnetically connected to each other at a position that is recessed from the surface facing a recording medium in the height direction. In addition, coil layers for applying a recording magnetic field to the main magnetic pole layer and the return yoke layer are provided in the non-magnetic insulating layer. In the magnetic head device having the above-mentioned structure, when a current flows through the coil layers, a recording magnetic field is formed between the main magnetic pole layer and the return yoke layer, and the recording magnetic field is vertically applied to a hard film of a recording medium from the surface of the main magnetic pole layer facing the recording medium to reach a soft film of the recording medium. Then, the recording magnetic field returns to the return yoke layer. In this way, information is recorded in a region of the recording medium facing the main magnetic pole layer (see JP-A-2005-122831).
In the vertical magnetic recording head device, the return yoke layer or a shield layer is generally formed of a substantially rectangular thin film magnetic body. When an external magnetic field is applied in the height direction, the magnetic flux in the magnetic body is concentrated on the edge of the thin film. In this case, the number of magnetization components in the height direction is the largest, which causes the overwriting of information (edge write). That is, in order to weaken an edge write magnetic field, it is necessary to reduce magnetic field components generated from the edge of the return yoke layer or the shield layer in the height direction.